Compression refrigeration working fluid



Feb. 16, 1965 a. HEROLD 3,159,923

COMPRESSION mum-non wonxms FLUID Filed Feb. 24, 1959 1 MIXED BASE MINERALOIL 30"- A 2 PARAFFIN g BASE MINERAIOIL Q) o 10 2 5g TEMPERATURE (c I 1 3 NADHTHENIC BASE MINERALOIL t MISCIBILITY OF SYNTHETIC OIL ACCORDING TO EXAMPLE I,WITH

IFIUOROMONOCHIORMETHANE 5 MISCIBILITY OF SYNTHETIC OIL ACCORDING TO EXAMPLES WITH DI FIUOROMONOCHLORMETHANE 16 3 0 5 0 60 16% PROPORTION OFOII. IN DIFLUOROMONOCHLORMEIHANE INVENTOR 'Pamd 4W4 M W AW 3,169,928 COMPRESSION REFRlgERATION WORKING FL ID Bernd Herold, Mulilenstrasse 53, Ludinghausen, Germany Filed Feb. 24, 1959, Ser. No. 795,181 3 Claims. (Cl. 252-68) This invention relates to lubricating compositions for refrigerating machines and it has particular relation to compression refrigerating machines operated with halogenated hydrocarbons. 7

It has been known to use as refrigerating agents in refrigerating machines difluoromonochloromethane, difiuorodichloromethane and methyl chloride. It has been also known that difluoromonochloromethane has certain essential advantages in comparison with the use of difluorodichloromethane which has been primarily used I up to now. For example, difiuoromonochloromethane is 1.6l.7 times superior in its volumetric refrigerating capacity to difiuorodichloromethanc. Furthermore, in refrigerating machines operated with ditluoromonochloromethane, lower cooling temperatures can be obtained in one step operation than with difluorodichloromethane under otherwise equal conditions.

However, it is a disadvantage thatin contrast to difluorodichloromethanedifiuoromonochloromethane is not completely miscible with themineral oils conventionally used as lubricating agents at low temperatures, as indicated by curves 1-3 of the appended drawing. The consequence of this is that expensive oil separators and .oil return devices must be built in refrigerating machines operated with difiuoromonochloromethane.

It has been known that oils having a naphthenic base (see curve 3 of the drawing) can be completely mixed ith diiluoromonochloromethane at lower temperatures than oils having a mixed naphthenic, or paraffinic base (see curves 1 and 2). However, the miscibility at low temperatures of difiuoromonoc. loromethane with even very good oils having a naphthenic base is by far not sufiicient for rendering dispensable the use of oil separators and oil return devices in refrigerating machines.

In order to overcome the above mentioned disadvantages occurring in the use of ditluorombnochloromethane, instead of mineral oils, secondary silieie acid butyl esters (silicones) have been used as lubricating agents. It has been found that such esters are well miscible with difiubromonochloromethane so that the use of oil separators and oil return devices could be dispensed with. However, the use of said esters has the disadvantage that they are relatively expensive and their lubricating effect is lower than that of mineral oils.

It has now been unexpectedly found that synthetic oils of the type described hereinafter and obtained by condensation of olefins or halogen alkyls with aromatic hydrocarbons, are completely miscible with diflupromonochloromethane up to very low temperatures and that they meet the conventional requirements of stability to refrigerating agents. The stability of these synthetic products to difluorodichloromethane and to methyl chloride is likewise satisfactory and no copper plating occurs in their use. In mixtures of ditluorodichloromethanc with said synthetic products, the temperatures at which Separation into the individual ingredients occurs are considerably lower than the corresponding separation temperatures in mixtures of the synthetic products with difiuoromonochloromethane. This has been observed aldo in the use of comparable conventional oils. The oils embodying the present invention can be universally utilized in refrigerating machines operated with difluoromonochloromethane, difiuorodichloromethane and methyl chloride. The distillation residues obtained in the preparation of monoalkyl benzenes are particularly suitable t for use according to the present invention.

Adjustment of the viscosity, flowing capacity at low temperatures, flash point, and average molecular weight, is carried out according to the present invention in such a manner that the requirements of DIN 51,503 as well as the requirement of complete miscibility with difluoromonoehloromethane in all mixing proportions, up to temperatures of at least -25 C., are met and no paratfin separations occur.

The synthetic lubricating oils of the present invention, or fractions of these oils, can be mixed with lubricating oils which, by themselves, are not, or not sutliciently, miscible for example with difiuoromonochloromethane up to the desired temperatures in all mixing proportions. It has been found that by the admixture of oils of the present invention to other, e.g., conventional lubricating oils the miscibility minimum can be shifted in many variations up to the desired low temperatures.

In order to obtain the stability to refrigerating agent s callcd'for by DIN 51,503 and the low neutralization and saponir'ication numbers likewise called for by said standard requirement, as well as in order to avoid copperplating, it is contemplated according to the present invention to treat the oils of the invention with absorbing agents in order to reduce the resin content and the content of acid and/or saponifiable components in said oils. x

Example 1 A distillation residue obtained in the preparation (if monoalkyl benzene from benzene and straight chain olefins consisting substantially of compounds having a chain length of C -C said residue boiling above 210/l2 mm. was subjected to a further vacuum distillation, in which 81% by volume of the residue subjected to distillation was obtained as distillate. After treatment with bleach ing earth, this polyalkylated benzene distillate oil had the following characteristics:

Stability to refrigerating agents Over 96 hours. Miscibility with difluoromonochloi romethane See curve 4 of the drawing.

Example 2 A distillation residue obtained in the preparation of monoalkyl benzene from benzene and tetramer propylene, which boiled above 2l0/l2 mm., was subjected to a further distillation under vacuum, in which by volume of said residue were obtained as distillate. After I 3,169,928 Patented Feb. 1 6, 1965 treatment with bleaching earth the polyalkylated benzene oilhad the following characteristics:

Viscosity at 20C 36.6 E. Viscosity at 50 C 5.0' E. 11/20 0. 0.874. Flash point 175 C. solidifying point 34 C.

Acid number 0.01. Saponification number 0.1.

Flowing capacity at low tem- I perature according to vDIN i 51,568 4 mm./60 sec. at 25 C-.'

Stability to refrigerating agents Over 96 hours.

Mixtures of this oil with difiuoromonochloromethane,

which contained in one case- 17.1 and in a second case 10.3% of the oil, showed separation only at temperaturesof 64 C. and below 65 C., respectively.

Example 3 the following characteristics:

Viscosity at 20 C 9.45 E. Viscosity at 50 C 2.7 E. d/ZO" C. 0.900.v Flash point 208 C. solidifying point -50 C.

Acid number 0.01. Saponification number 0.2.

Flowing capacity at low tempernture according to DIN 51,658 --20 mum/13.1 sec. at -25 C.

Stability to refrigerating agents Over 96 hours.

The separation or segregation temperatures of mixtures of difiuoromonochloromethane containing (a) '15 .3% and (b) 9.5% synthetic oil of this example, were at (a) 57 C. and (b) 65 C.

Example 4 A distillation residue boilingabove 190 C./l2 mm.

and obtained in the preparation of monoalkyl benzene by reacting benzene with a dodecene, of theisobutene type,

obtained by dimerization of n-hexane, is subjected to further distillation under vacuum, whereby about 75% by volume of the residue distilled, were obtained as distillate. After bleaching with bleaching earth, the polyalkylated benzene distillate oil hadthe following characteristics:

A mixture of this oil with ditluoromonochloromethane containing 13.6% of the oil did not show separation upon cooling to 70 C.

Example 5 A conventional commercial lubricating mineralroil of low viscosity for refrigerating machines was mixed in the proportion 1:1 with the alkylation residue distillate described in the above Example 2. This mixture had the following characteristics:

Viscosity at 20 C. 13.7 E. Viscosity at 50 C. 2.9 E. d/ZO. C 0.884. Flash point 183 C. solidifying point 42 C. Acid number- 0.05. Saponification number 0.1.

Flowing capacity at low temperature according to DIN 51,568 20 rum/52.7 sec. at --25 C.

Mixtures of this oil with difluoromonochloromethane, which contained (a) 3.01% and (b) 12.1% of said oil, showed separation at (a) --51" C. and (b) -33 C.

Example 6 A highly viscous, conventional commercial lubricating mineral oil was mixed in the proportion of 30:70 with the alkylation residue described in the above Example 3., This mixture had the following characteristics:

Viscosity at 20 C. 11.6 E. Viscosity at 50 C. 2.8 E. d/20" C. 0.901. Flash point 198 C. solidifying point 49 C. Acidnumber 0.06. Saponification number 0.1. Flowing capacity at low temperature according to DIN 51,568 20 mm./22.6 sec. at 25 C'.

Miscibility with difluorornonochloromethane is shown incurve 5 of the drawing.

The term bleaching earth is used herein to denote materials which have strong absorbent capacity and are used, among others, for the purification of oils by absorption, such as fullers earth, bentonite, Florida bleaching earth and the like.

The preparation of synthetic oils in the above described manner, e.g., by condensation from benzene and olefin hydrocarbons, has been known by itself from the art and is described, for example, in the German patents No. 767,299 and 895,588.

The temperatures stated herein are centig'rade, and the parts mentioned are by weight, if not otherwise stated. The term terminal olefin is used herein to denote olefins, in which the double bond is located between the last two C-atoms of the chain.

The residues mentioned in the above examples are. preferably distilled up to a temperature of about 330 C. under a vacuum of about 12 mm.

It will be understood from the above that this invention is not limited to the specificmaterials, steps, conditions and other details specifically described above and can be carried out with various modifications without departing from the scope of the invention as defined in the appended claims.

It will be also understood that the appended drawing illustrates the miscibility of difiuoromonochloromethane with various mineral oils at various temperatures (curves 1, 2, 3) and the miscibility of synthetic oils embodying the present invention (curves 4 and 5) as indicated by the legends in the drawing.

The abbreviation- DIN is used herein to denote the standards published by the Deutsche Industrie Normung (German Industrial Standardization). The abbreviation d is used to denote density and the abbreviation E is used to denote Englcr degrees. of viscosity.

5 What is claimed is: 1. A compression refrigeration working fluid consisting essentially of (1) from 75% to 97% of a halogenerated aliphatic hydrocarbon refrigerant, and, (2) from 3% to 25% of a lubricating oil consisting essentially of,

(a) to 50% of a petroleum mineral oil, and (b) 100% to 50% of a polyalkylated benezene distillation residue having,

(i) an initial boiling point between 150 C. 12 mm. Hg and 210 C. 12 mm. Hg, (ii) a final boiling point of about 330 C.

12 mm. Hg, (iii) a viscosity at 20 C. between 9 and 37" E., (iv) a viscosity at 50 C. between 2 and 15., said working fluid remaining single phase at 25 C.

2. The compression refrigeration working fluid of claim 1 wherein said refrigerant is selected from the group consisting of difiuoromonochloromethane, difiuorodichloromethane, and methyl chloride.

- 6 3. The compression refrigeration working fluid of claim 2 wherein said refrigerant is difiuoromonochloromethane.

References Cited in the file of this vpatent UNITED STATES PATENTS 2,138,775 Towne Nov. 29, 1938 2,141,593 Clarke et a1 Dec. 27, 1,938 2,424,956 Reitf et al July 29, 1947 2,477,382 Lewis July 26, 1949 2,810,769 Sanford et al Oct. 22, 1957 3,092,981 Begeman et a1 June 11, 1963 FOREIGN PATENTS 141,291 Australia May 18, 1951 216,100 Australia -5. July 23, 1958 1,163,023 France Apr. 21, 1958 767,299 Germany May 2, 1952 895,588 Germany Nov. 5, 1953 675,842 Great Britain July 16, 1952 803,564 Great Britain Oct. 29, 1958 

1. A COMPRESSION REFRIGERATION WORKING FLUID CONSISTING ESSENTIALLY OF (1) FROM 75% TO 97% OF A HALOGENERATED ALIPHATIC HYDROCARBON REFRIGERANT, AND, (2) FROM 3% TO 25% OF A LUBRICATING OIL CONSISTING ESSENTIALLY OF, (A) 0% TO 50% OF A PETROLEUM MINERAL OIL, AND (B) 100% TO 50% OF A POLYALKYLATED BENEZENE DISTILLATION RESIDUE HAVING, (I) AN INITIAL BOILING POINT BETWEEN 150*C. @ 12 MM. HG AND 210*C. @ 12MM.HG, (II) A FINAL BOILING POINT OF ABOUT 330*C. @ 12MM.HG, (III) A VISCOSITY AT 20*C. BETWEEN 9* AND 37*E., 